I started using dual control a year or so ago, and found the shifting very intuitive; from day one I took to it like a duck to water. I've never had any mechanical problems with the shifters (touch wood), and I'm quite rough on my bikes considering that they're all xc orientated. I did however have a bit of trouble fitting them on an FSA low riser bar- I think they're designed with flats in mind. I can fit them comfortably on a easton or raceface low riser, it just meant the added expense of buying new bars.
True that you must use shimano brakes, but then shimano brakes are pretty good, so I don't mind that.